Created a JsonAdapter annotation that can be applied to classes to indicate their TypeAdapter.
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@ -24,6 +24,7 @@ import com.google.gson.internal.bind.ArrayTypeAdapter;
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import com.google.gson.internal.bind.CollectionTypeAdapterFactory;
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import com.google.gson.internal.bind.CollectionTypeAdapterFactory;
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import com.google.gson.internal.bind.DateTypeAdapter;
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import com.google.gson.internal.bind.DateTypeAdapter;
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import com.google.gson.internal.bind.FieldTypeAdapterFactory;
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import com.google.gson.internal.bind.FieldTypeAdapterFactory;
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import com.google.gson.internal.bind.JsonAdapterAnnotationTypeAdapterFactory;
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import com.google.gson.internal.bind.JsonTreeReader;
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import com.google.gson.internal.bind.JsonTreeReader;
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import com.google.gson.internal.bind.JsonTreeWriter;
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import com.google.gson.internal.bind.JsonTreeWriter;
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import com.google.gson.internal.bind.MapTypeAdapterFactory;
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import com.google.gson.internal.bind.MapTypeAdapterFactory;
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@ -238,6 +239,7 @@ public final class Gson {
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// type adapters for composite and user-defined types
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// type adapters for composite and user-defined types
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factories.add(new CollectionTypeAdapterFactory(constructorConstructor));
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factories.add(new CollectionTypeAdapterFactory(constructorConstructor));
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factories.add(new MapTypeAdapterFactory(constructorConstructor, complexMapKeySerialization));
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factories.add(new MapTypeAdapterFactory(constructorConstructor, complexMapKeySerialization));
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factories.add(new JsonAdapterAnnotationTypeAdapterFactory(constructorConstructor));
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factories.add(new FieldTypeAdapterFactory());
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factories.add(new FieldTypeAdapterFactory());
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factories.add(new ReflectiveTypeAdapterFactory(
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factories.add(new ReflectiveTypeAdapterFactory(
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constructorConstructor, fieldNamingPolicy, excluder));
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constructorConstructor, fieldNamingPolicy, excluder));
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@ -0,0 +1,80 @@
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/*
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* Copyright (C) 2014 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson.annotations;
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import java.lang.annotation.ElementType;
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import java.lang.annotation.Retention;
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import java.lang.annotation.RetentionPolicy;
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import java.lang.annotation.Target;
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import com.google.gson.TypeAdapter;
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/**
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* An annotation that indicates the Gson {@link TypeAdapter} to use with a class or a field.
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* Any type adapters registered in {@link com.google.gson.GsonBuilder} supersede the adapter
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* specified in this annotation.
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*
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* <p>Here is an example of how this annotation is used:</p>
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* <pre>
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* @JsonAdapter(UserJsonAdapter.class)
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* public class User {
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* public final String firstName, lastName;
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* private User(String firstName, String lastName) {
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* this.firstName = firstName;
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* this.lastName = lastName;
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* }
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* }
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* public class UserJsonAdapter extends TypeAdapter<User> {
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* @Override public void write(JsonWriter out, User user) throws IOException {
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* // implement write: combine firstName and lastName into name
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* out.beginObject();
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* out.name("name");
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* out.value(user.firstName + " " + user.lastName);
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* out.endObject();
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* // implement the write method
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* }
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* @Override public User read(JsonReader in) throws IOException {
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* // implement read: split name into firstName and lastName
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* in.beginObject();
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* in.nextName();
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* String[] nameParts = in.nextString().split(" ");
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* in.endObject();
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* return new User(nameParts[0], nameParts[1]);
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* }
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* }
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* </pre>
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*
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* Since User class specified UserJsonAdapter.class in @JsonAdapter annotation, it
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* will automatically be invoked to serialize/deserialize User instances.
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*
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* If the UserJsonAdapter needs a constructor other than a no-args constructor, you must register
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* an {@link com.google.gson.InstanceCreator} for it.
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*
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* @since 2.3
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*
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* @author Inderjeet Singh
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* @author Joel Leitch
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* @author Jesse Leitch
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*/
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// Note that the above example is taken from JsonAdapterANnotationTest.
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@Retention(RetentionPolicy.RUNTIME)
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@Target(ElementType.TYPE)
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public @interface JsonAdapter {
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Class<? extends TypeAdapter<?>> value();
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}
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@ -0,0 +1,51 @@
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/*
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* Copyright (C) 2014 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson.internal.bind;
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import com.google.gson.Gson;
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import com.google.gson.TypeAdapter;
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import com.google.gson.TypeAdapterFactory;
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import com.google.gson.annotations.JsonAdapter;
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import com.google.gson.internal.ConstructorConstructor;
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import com.google.gson.internal.ObjectConstructor;
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import com.google.gson.reflect.TypeToken;
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/**
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* Given a type T, looks for the annotation {@link JsonAdapter} and uses an instance of the
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* specified class as the default type adapter.
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*
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* @since 2.3
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*/
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public final class JsonAdapterAnnotationTypeAdapterFactory implements TypeAdapterFactory {
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private final ConstructorConstructor constructorConstructor;
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public JsonAdapterAnnotationTypeAdapterFactory(ConstructorConstructor constructorConstructor) {
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this.constructorConstructor = constructorConstructor;
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}
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@SuppressWarnings({ "rawtypes", "unchecked" })
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public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> targetType) {
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Class<? super T> clazz = targetType.getRawType();
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JsonAdapter annotation = clazz.getAnnotation(JsonAdapter.class);
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if (annotation == null) return null;
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Class<? extends TypeAdapter<?>> adapterClass = annotation.value();
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ObjectConstructor<? extends TypeAdapter<?>> constructor = constructorConstructor.get(TypeToken.get(adapterClass));
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TypeAdapter adapter = constructor.construct();
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return adapter;
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}
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}
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@ -0,0 +1,182 @@
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/*
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* Copyright (C) 2014 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.gson.functional;
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import java.io.IOException;
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import java.lang.reflect.Type;
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import junit.framework.TestCase;
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import com.google.gson.Gson;
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import com.google.gson.GsonBuilder;
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import com.google.gson.JsonDeserializationContext;
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import com.google.gson.JsonDeserializer;
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import com.google.gson.JsonElement;
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import com.google.gson.JsonParseException;
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import com.google.gson.JsonPrimitive;
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import com.google.gson.JsonSerializationContext;
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import com.google.gson.JsonSerializer;
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import com.google.gson.TypeAdapter;
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import com.google.gson.annotations.JsonAdapter;
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import com.google.gson.stream.JsonReader;
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import com.google.gson.stream.JsonWriter;
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/**
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* Functional tests for the {@link com.google.gson.annotations.JsonAdapter} annotation.
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*/
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public final class JsonAdapterAnnotationTest extends TestCase {
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public void testJsonAdapterInvoked() {
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Gson gson = new Gson();
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String json = gson.toJson(new A("bar"));
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assertEquals("\"jsonAdapter\"", json);
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// Also invoke the JsonAdapter javadoc sample
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json = gson.toJson(new User("Inderjeet", "Singh"));
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assertEquals("{\"name\":\"Inderjeet Singh\"}", json);
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User user = gson.fromJson("{'name':'Joel Leitch'}", User.class);
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assertEquals("Joel", user.firstName);
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assertEquals("Leitch", user.lastName);
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}
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public void testRegisteredAdapterOverridesJsonAdapter() {
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TypeAdapter<A> typeAdapter = new TypeAdapter<A>() {
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@Override public void write(JsonWriter out, A value) throws IOException {
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out.value("registeredAdapter");
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}
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@Override public A read(JsonReader in) throws IOException {
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return new A(in.nextString());
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}
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};
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Gson gson = new GsonBuilder()
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.registerTypeAdapter(A.class, typeAdapter)
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.create();
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String json = gson.toJson(new A("abcd"));
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assertEquals("\"registeredAdapter\"", json);
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}
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/**
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* The serializer overrides field adapter, but for deserializer the fieldAdapter is used.
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*/
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public void testRegisteredSerializerOverridesJsonAdapter() {
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JsonSerializer<A> serializer = new JsonSerializer<A>() {
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public JsonElement serialize(A src, Type typeOfSrc,
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JsonSerializationContext context) {
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return new JsonPrimitive("registeredSerializer");
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}
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};
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Gson gson = new GsonBuilder()
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.registerTypeAdapter(A.class, serializer)
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.create();
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String json = gson.toJson(new A("abcd"));
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assertEquals("\"registeredSerializer\"", json);
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A target = gson.fromJson("abcd", A.class);
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assertEquals("jsonAdapter", target.value);
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}
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/**
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* The deserializer overrides Json adapter, but for serializer the jsonAdapter is used.
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*/
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public void testRegisteredDeserializerOverridesJsonAdapter() {
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JsonDeserializer<A> deserializer = new JsonDeserializer<A>() {
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public A deserialize(JsonElement json, Type typeOfT,
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JsonDeserializationContext context) throws JsonParseException {
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return new A("registeredDeserializer");
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}
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};
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Gson gson = new GsonBuilder()
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.registerTypeAdapter(A.class, deserializer)
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.create();
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String json = gson.toJson(new A("abcd"));
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assertEquals("\"jsonAdapter\"", json);
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A target = gson.fromJson("abcd", A.class);
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assertEquals("registeredDeserializer", target.value);
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}
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public void testIncorrectTypeAdapterFails() {
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try {
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String json = new Gson().toJson(new ClassWithIncorrectJsonAdapter("bar"));
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fail(json);
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} catch (ClassCastException expected) {}
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}
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public void testSuperclassTypeAdapterNotInvoked() {
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String json = new Gson().toJson(new B("bar"));
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assertFalse(json.contains("jsonAdapter"));
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}
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@JsonAdapter(A.JsonAdapter.class)
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private static class A {
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final String value;
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A(String value) {
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this.value = value;
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}
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private static final class JsonAdapter extends TypeAdapter<A> {
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@Override public void write(JsonWriter out, A value) throws IOException {
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out.value("jsonAdapter");
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}
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@Override public A read(JsonReader in) throws IOException {
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in.nextString();
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return new A("jsonAdapter");
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}
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}
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}
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private static final class B extends A {
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B(String value) {
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super(value);
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}
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}
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// Note that the type is NOT TypeAdapter<ClassWithIncorrectJsonAdapter> so this
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// should cause error
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@JsonAdapter(A.JsonAdapter.class)
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private static final class ClassWithIncorrectJsonAdapter {
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@SuppressWarnings("unused") final String value;
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ClassWithIncorrectJsonAdapter(String value) {
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this.value = value;
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}
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}
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// This class is used in JsonAdapter Javadoc as an example
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@JsonAdapter(UserJsonAdapter.class)
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private static class User {
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public final String firstName, lastName;
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private User(String firstName, String lastName) {
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this.firstName = firstName;
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this.lastName = lastName;
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}
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}
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private static class UserJsonAdapter extends TypeAdapter<User> {
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@Override public void write(JsonWriter out, User user) throws IOException {
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// implement write: combine firstName and lastName into name
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out.beginObject();
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out.name("name");
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out.value(user.firstName + " " + user.lastName);
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out.endObject();
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// implement the write method
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}
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@Override public User read(JsonReader in) throws IOException {
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// implement read: split name into firstName and lastName
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in.beginObject();
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in.nextName();
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String[] nameParts = in.nextString().split(" ");
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in.endObject();
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return new User(nameParts[0], nameParts[1]);
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}
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}
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}
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